The present invention relates to air bag apparatuses mounted in vehicles, etc., and more specifically relates to an air bag apparatus for a driver""s seat which has horn switches.
Generally, air bag apparatuses for driver""s seats of vehicles include an air bag which is folded and is fixed to a retainer (also referred to as a container, etc.) at an end thereof, and a module cover which is attached to the retainer for covering the folded air bag. In addition, an inflator (gas generator), which generates a gas for inflating the air bag, is usually attached to the retainer. When a vehicle collides, the inflator generates a gas and starts to inflate the air bag. Then, the module cover breaks and opens, and the air bag expands toward the driver.
The module cover is provided with a tear line (also referred to as a thinned portion or as a weakened portion), along which the module cover breaks and opens when it is pressed from behind by the inflated air bag.
FIG. 12 and FIG. 13 are perspective views of steering wheels containing conventional air bag apparatuses. In the figures, the upper sides of the steering wheels are not shown. With reference to the figures, air bag apparatuses 2A and 2B are contained inside steering wheels 1. Module covers 3A and 3B of the air bag apparatuses 2A and 2B, respectively, are provided with attaching portions 4 which are attached to spoke portions 1a of the steering wheels 1. The air bag apparatus 2A has four attaching portions 4, and the air bag apparatus 2B has three attaching portions 4. In addition, each of the module covers 3A and 3B has tear lines 5.
In certain air bag apparatuses for driver""s seats as described above, horn switches are triggered and a horn is activated by pressing the module cover. There are two types of air bag apparatuses with such horn switches. In one type, the entire body of the air bag apparatus moves backward, and in the other type, only the module cover moves backward.
If the central region of the air bag apparatus is pressed to activate the horn, the entire air bag apparatus or only the module cover moves backward uniformly over the entire region thereof. However, typically a region near the periphery of the air bag apparatus is pressed, so that only the side at which the module cover is pressed moves backward, and the other side moves only slightly. As a result, the air bag apparatus tilts.
Accordingly, guide holes, which are provided for guiding the movement of the air bag apparatus or only the module cover, must have sufficient diameters so that, regardless of the direction in which the air bag apparatus tilts, guiding shafts do not knock against the inner walls of the guide holes.
When the guide holes have large diameters, however, the positional accuracy of the air bag apparatus or of the module cover is degraded. Thus, displacement between the attaching portions and the spoke portions of the steering wheel occur.
Accordingly, an object of the present invention is to provide an air bag apparatus which does not cause the above-described displacement, and of which the entire body or the module cover is easily positioned with high accuracy.
According to one aspect of the present invention, a driver-seat air bag apparatus is contained in a steering wheel, and comprises three horn switches which are circularly disposed at three positions in the steering wheel, each of the horn switches including a movable member which is provided with an opening and a contacting point, and which moves, when the air bag is pressed, in the direction in which the air bag is pressed; a guide shaft which is inserted through the opening and which guides the movement of the movable member; and a biasing member which applies biasing force to the movable member in the direction opposite to the direction in which the air bag is pressed. The opening in each of the horn switches is formed as an oblong hole which extends perpendicularly to a line which passes through between the other two horn switches.
When the air bag apparatus or the module cover is pressed and moves backward, the guide shaft moves inside the opening (guide hole) of the movable member. At this time, according to the present invention, the guide shaft in each of the horn switches moves perpendicularly to the line which passes through the other two horn switches. Thus, it is only necessary that the guide hole extends in this direction.
According to the above-described air bag apparatus in which the guide hole in each of the horn switches is formed as an oblong hole, the air bag apparatus or the module cover is positioned with high accuracy in the lateral direction of the guide hole. Thus, the displacement between the attaching portions of the module cover and the spoke portions of the steering wheel is prevented.
In addition, according to another aspect of the present invention, a driver-seat air bag apparatus is contained in a steering wheel, and comprises three horn switches which are circularly disposed at three positions in the steering wheel, each of the horn switches including a movable member which is provided with a contacting point, and which moves, when the air bag apparatus is pressed; in the direction in which the air bag is pressed, a guide shaft which is fixed to the movable member and which moves along with the movable member; a fixed portion which is provided with an opening through which the guide shaft is inserted, and a biasing member which applies biasing force to the movable member in the direction opposite to the direction in which the air bag is pressed. The opening in each of the horn switches is formed as an oblong hole which extends perpendicularly to a line which passes through between the other two horn switches.
Also in such an air bag apparatus, the opening (guide hole) in each of the horn switches is formed as an oblong hole. Accordingly, the air bag apparatus or the module cover is positioned with high accuracy in the lateral direction of the guide hole. Thus, the displacement between the attaching portions of the module cover and the spoke portions of the steering wheel are prevented.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.